Bilirubin and biliverdin, both byproducts of heme degradation, have long been studied for their physiological roles in human health. While historically associated with jaundice, these compounds have recently gained attention for their potential beneficial effects, extending beyond their traditionally perceived toxic nature. This article aims to explore and shed light on the diverse functions of bilirubin and biliverdin, highlighting their contributions to human health.
Bilirubin, often associated with a yellowish pigmentation of skin and eyes in cases of excessive accumulation, undergoes a series of enzymatic reactions in the liver to become water-soluble and easily excreted. However, recent research has indicated that modestly elevated levels of bilirubin can confer antioxidant and anti-inflammatory properties. Bilirubin acts as a potent scavenger of reactive oxygen species (ROS) and inhibits the oxidation of lipids, thereby protecting against oxidative stress-related damage in various organs and systems.
In addition to its antioxidant effects, bilirubin has also demonstrated anti-inflammatory properties. It has been found to suppress the production of pro-inflammatory cytokines, impede the activation of Nuclear Factor-κB (NFκB), and inhibit the expression of adhesion molecules. By modulating these inflammatory processes, bilirubin potentially plays a crucial role in limiting tissue injury and preventing chronic inflammatory diseases such as atherosclerosis, diabetes, and even certain types of cancer.
Further exploration of bilirubin’s physiological role has unveiled its potential impact on cardiovascular health. Multiple studies have reported an inverse relationship between bilirubin levels and the incidence of cardiovascular diseases, including coronary artery disease, heart failure, and stroke. Bilirubin’s antioxidant and anti-inflammatory properties are believed to contribute to this protective effect. It has been suggested that bilirubin inhibits the oxidation of low-density lipoprotein (LDL) cholesterol, a key event in the formation of atherosclerotic plaques.
Moving on to biliverdin, the green pigment generated during heme degradation, its physiological role has received comparatively less attention. However, recent studies have begun to unravel its potential significance. Biliverdin has been found to possess antioxidant properties similar to bilirubin, although generally less potent. It acts as a scavenger of ROS and attenuates oxidative stress-induced damage. In addition, biliverdin has been implicated in the regulation of cellular proliferation, differentiation, and apoptosis, suggesting its involvement in various cellular processes.
Exploring the role of biliverdin in different diseases has revealed its potential impact on neurodegenerative disorders, such as Alzheimer’s and Parkinson’s disease. By inhibiting the formation of toxic aggregates and reducing neuroinflammation, biliverdin may help prevent or slow the progression of these debilitating conditions. Moreover, biliverdin has shown promise in protecting against liver injury, kidney disease, and ocular disorders, indicating its multifaceted contributions to human health.
In conclusion, the traditional view of bilirubin and biliverdin as toxic compounds overshadowed their potential therapeutic benefits. Recent discoveries have opened the door to explore their physiological roles beyond jaundice and toxicity. Bilirubin’s antioxidant and anti-inflammatory properties, its association with cardiovascular health, and biliverdin’s protective effects against neurodegenerative and other diseases highlight their importance in maintaining human health. Continued research in this field may uncover novel therapeutic targets and strategies to harness the potential of these compounds for the prevention and treatment of various diseases.